Can't speak specifically without the trimsheet and manuals.
However, it is usual for the trimsheet designer to develop conservative practical limits from an error analysis of the trimsheet design.
Generating an excel application for the specific trimsheet is straightforward .. just reverse engineer the trimsheet to get the numbers for the spreadsheet. If you are not sure how to do that, provide some scans of the documents and we can give you a hand .. Unless the trimsheet is a dog's breakfast accuracy won't be a problem.